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Whats a good carb for a 220 GPU?

John C

John C

Well-known member
I went riding yesterday with Florida Cracker and another friend of mine. My friend has a 13 ft. glass hull with a 220 GPU. He asked me what the best carb for that motor was. I dont know anything about a GPU. But I told him that I would ask. He has a 2 Brl. Holley on it now. want to know if you can go any bigger. Maybe dump a little more fuel, make a little more power.
 
I have found that a holley 500cfm 2 barrel is the perfect carb for a 470 gpu. The ones I have set up used between 72-78 main jets, depending on how motor was built and exhaust setup.

Larry
 
I had the same setup Larry has and it worked great. One of the things you have to look at is the intake manifold. I personally think the ones that mount from the front of the stock manifold are the best, the front mount allows the fuel to flow the way Continental designed them. The top mount carb, from what I am told, sometimes does not allow all the cylinders to get enough gas. The motor I had was built by Chuck Rackley when he was at Hoffman Airboats. Chuck is now at Airboat Pros. He is the man to talk to reguarding anything related to those 220 GPU's.
 
Thank you for the quick reply. I will have to check with him and see what cfm his carb is, and what size the jets are.
 
Rdm, is this like you were talking about? This is the adapter that my dad's gpu has on it. I think it may be from Medland, not positive. The drawbacks to this adapter are it with ice over when the weather is below 40deg(I have seen it almost 1/4in. thick on it), and it will let fuel puddle up and flood the motor easily. Other then those 2 problems it seem to work real well.

carb.jpg



Larry
 
Yep, that is it. Now that you mention it mine did ice up also, never as thick as you mentioned but it did happen. I never had problems with flooding but I can see how it can happen. I have since moved to a straingt valve 0540 but I keep in touch with the guy that bought my last boat, and it is still running strong. You really cannot beat those GPU's, they are great motors.
 
If running the holly 500, I would suggest running 77 jets and increase the power valve to a 10.5 . Those can be found at speed shops or online performance shops. I would also recommend a Dave Stratton prepared intake. He and Dick Hoffmann worked many hours developing the best flow characteristics of the GPU. Paul Dixon, up in Bainbridge,Ga., is finding that using the Edelbrok performer 600 cfm stock out of the box on a Stratton intake has more power and uses less fuel.

Also, Icing is a good thing.

Dave Stratton Airboat Accessories@ 352-860-0022
Tell him Bob Hoover sent ya.
 
Guess I've lived in Florida too long. I always figured the only place ice had was in my drink or cooler. Anything else and I'm ready to move further south ! SHIVVVVVVVER Grinn :)

Scotty
 
Whitebear, If you'd get away from them car boats you'd see what I mean :wink: . When I had a GPU, it would have ice after hard running on a 90 degree day. Now I've got a 520 with carb and it gets real frosty :lol: . Have big foot, get more ice :D .
 
Actually Carb icing isn't good. It chokes the engine and makes it run richer than normal. We have a problem up here with even our Carb watercooled engines and the problem has to do with the temperature/dewpoint spread. The closer together the easier it is to ice up the carb. :roll: Check this out http://en.wikipedia.org/wiki/Carburetor_icing
 
Scotty, I wish you could walk around SwampJet's boat like I did last Sat. morning ..... it's as fine as any 520 Continental rig on the planet.

BF

PS: but my little car motor will have more torque :wink: .
 
Cold-eh, That refers to iceing IN the carb, what we have here (in Paradise better known as Florida) with the humid conditions is iceing On the manifold wih some on the carb. This is caused by the low pressure (vacuum) in the manifold. The better the vacuum, the more ice or at least condensation. Basic refrigeration physics.
Here in Fl., If a GPU is not getting at least condensation then something aint right.
 
Well maybe Feather But your riding my boat this weekend and you might have to drive it so I can be passenger for once :lol:.
Besides, your right arm might get tired from sticking all those frogs you'll have to balance it out by driving :D .
 
Cold, ya gotta get over the idea that engines were designed to run at 40 below .... all of us are tryin to get the things to run at sea level and 92 deg. F.

BF
 
Scotty, Swamp knows how to turn up the heat when he wants to ..... :lol:

K.
 
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